Home and business alarms have become commonplace. Such alarms (often referred to as “security systems” or “alarm systems”) typically include several sensors used to monitor unauthorized entry and other conditions at monitored premises, such as fire, smoke, toxic gases, high/low temperature (e.g. freezing) or flooding, at a premises. In response to sensing an alarm condition, a sensor provides a signal to an alarm panel that in turn may sound and notify the occurrence of the alarm to occupants of the premises and remotely signal a monitoring center or other third party.
Typically the occurrence of an alarm is signalled to a remote monitoring center that may then dispatch capable authorities to intervene at the premises. For example, in the case of sensing an unauthorized entry to the premises, the monitoring center may dispatch security personnel, typically in the form of private security guards or police officers.
Additionally, many alarm systems now allow audio communication with the monitoring center. Such audio communication may be one-way (e.g. from the premises to the station) or two-way (i.e. from and to the premises/monitoring center). In this way, the alarm system may be used to audibly monitor the premises during an alarm condition, or it may be used to dispatch a verbal request for help by an occupant at the monitored premises. To this end, some alarm systems are equipped with an audio interface, including a microphone and optionally a speaker.
Communication between the premises and the monitoring station typically takes place over a communications network, for example by way of the public switched telephone network (PSTN).
Unfortunately, audio interfaces are susceptible to unauthorized modification, or disconnection by intruders or others. Tampering can be deterred by encasing the audio interface. This however, is costly and cumbersome. Alternatively, tampering can be detected.
Accordingly there is a need for alarm systems and audio interfaces that allow tamper detection.